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The 2nd law of thermodynamics and the greenhouse effect

Posted on 22 October 2010 by TonyWildish

Skeptics sometimes claim that the explanation for global warming contradicts the second law of thermodynamics. But does it? To answer that, first, we need to know how global warming works. Then, we need to know what the second law of thermodynamics is, and how it applies to global warming. Global warming, in a nutshell, works like this:

The sun warms the Earth. The Earth and its atmosphere radiate heat away into space. They radiate most of the heat that is received from the sun, so the average temperature of the Earth stays more or less constant. Greenhouse gases trap some of the escaping heat closer to the Earth's surface, making it harder for it to shed that heat, so the Earth warms up in order to radiate the heat more effectively. So the greenhouse gases make the Earth warmer - like a blanket conserving body heat - and voila, you have global warming. See What is Global Warming and the Greenhouse Effect for a more detailed explanation.

The second law of thermodynamics has been stated in many ways. For us, Rudolf Clausius said it best:

"Heat generally cannot flow spontaneously from a material at lower temperature to a material at higher temperature."

So if you put something hot next to something cold, the hot thing won't get hotter, and the cold thing won't get colder. That's so obvious that it hardly needs a scientist to say it, we know this from our daily lives. If you put an ice-cube into your drink, the drink doesn't boil!

The skeptic tells us that, because the air, including the greenhouse gasses, is cooler than the surface of the Earth, it cannot warm the Earth. If it did, they say, that means heat would have to flow from cold to hot, in apparent violation of the second law of thermodynamics.

So have climate scientists made an elementary mistake? Of course not! The skeptic is ignoring the fact that the Earth is being warmed by the sun, which makes all the difference.

To see why, consider that blanket that keeps you warm. If your skin feels cold, wrapping yourself in a blanket can make you warmer. Why? Because your body is generating heat, and that heat is escaping from your body into the environment. When you wrap yourself in a blanket, the loss of heat is reduced, some is retained at the surface of your body, and you warm up. You get warmer because the heat that your body is generating cannot escape as fast as before.

If you put the blanket on a tailors dummy, which does not generate heat, it will have no effect. The dummy will not spontaneously get warmer. That's obvious too!

Is using a blanket an accurate model for global warming by greenhouse gases? Certainly there are differences in how the heat is created and lost, and our body can produce varying amounts of heat, unlike the near-constant heat we receive from the sun. But as far as the second law of thermodynamics goes, where we are only talking about the flow of heat, the comparison is good. The second law says nothing about how the heat is produced, only about how it flows between things.

To summarise: Heat from the sun warms the Earth, as heat from your body keeps you warm. The Earth loses heat to space, and your body loses heat to the environment. Greenhouse gases slow down the rate of heat-loss from the surface of the Earth, like a blanket that slows down the rate at which your body loses heat. The result is the same in both cases, the surface of the Earth, or of your body, gets warmer.

So global warming does not violate the second law of thermodynamics. And if someone tells you otherwise, just remember that you're a warm human being, and certainly nobody's dummy.

This post is the Basic Version (written by Tony Wildish) of the skeptic argument "The 2nd law of thermodynamics contradicts greenhouse theory".

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Comments 251 to 260 out of 260:

  1. Also, for what happens to the upper level photons, the graphic at jg's (meant for explaining stratospheric cooling) is useful. And dont forget DLR is measured, something damorel struggles to explain.
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  2. damorbel at 00:00 AM Ned has already said it, but i realize on reading what i wrote how it may be interpreted, the lapse rate, may be due to density/gravitational compression(which also effects path length), but the energy contained is due to energy in vrs path length out. As can be seen in the graphic in NEDs post. The stratosphere is an entirely different kettle o fish, it absorbs UV through O3, and is optically thick for UV, but is relatively transparent to LW, so CO2 cools it, But UV heats it from the top down, there is a thread on it here at the moment. In which there has been a bit o a discussion about the relevance of radiation to the lapse rate and convection.
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  3. Re #249 Ned you wrote:- "(due to GHGs), and keeping the lapse rate constant (not due to GHGs), implies warming of the surface. " Implies? isn't this a scientific matter, better please! I first saw this in John Houghton's book 'Raising altitude of emission'. You should look at the evidence. The height of the tropopause , which you are saying is changed with GHG concentration, also follows the mean surface temperature as it varies with latitude, so it is clear that the height of the troposphere is also a function of the local planetary temperature which, according to GH theory, is also a function of the albedo. Now what is the effect of CO2, does it decrease the albedo, thus raising the planetary temperature, does it change the lapse rate (as compared with raising the tropopause) or does it warm the surface without affecting either the height of the troposphere or the lapse rate, this last being the 'backradiation' model. Can you say wchich it is? The thing about the lapse rate is that it is substantially constant at 6.5K/km over the whole planet, independent of the local temperature and the height of the tropopause.
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  4. Re #252 Joe Blog you wrote:- "the energy contained is due to energy in vrs path length out. As can be seen in the graphic in NEDs post." The diagram in Ned's post shows the temperature of the surface and atmosphere changing without the height of the tropopause changing, this is absurd; check the gas laws, PV = RT. Further you wrote:- "The stratosphere is an entirely different ...UV through O3, ... But UV heats it from the top down." Which is a very important point since this 'downward' (actually incoming) radiation is absorbed (by O2 as well as O3, the O2 absorption creates the O3) raising the temperature and causing an inversion. If the back radiation of the GHE hypothesis was warming the surface it would also warm the other GHGs on its way down, just like the solar UV warms in the troposphere, also causing an inversion.
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  5. "The thing about the lapse rate is that it is substantially constant at 6.5K/km over the whole planet" One more bit of misinformation added by our hero. Yes, misinformation; given the huge amount of errors thrown here, it can not simply be a lack of knowledge. A bit offtopic but interesting reading from Monbiot.
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  6. Re #255 Riccardo, you wrote:- "One more bit of misinformation added by....." And the correct version is....(?)
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  7. damorbel as you may have noticed, I didn't continue the discussion with you before. Also, from my last comment it should be clear that I don't think you have any real interest in the science. Many people here spent a lot of time highlighting your errors and providing solid scientific ground. At a point you even said that you know better than textbooks on basic science. In response, you kept moving the goalpost, as it should be clear looking back at the discussion. There ìs a wealth of good informations out there, if your interest in the science was genuine your first step would have been to check your claims or accept the suggestions given here. My conclusion is that you're just trying to hijack the discussion and it's not my wish to provide more fuel.
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  8. @damorbel: "Now what is the effect of CO2, does it decrease the albedo" CO2 is largely transparent to visible light. You've been called on to stop your misinformation. Why won't you?
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  9. Re 257 Riccardo I am interested in your own ideas on climate matters. I have read plenty of posts anI am also very familiar with the arguments put forward for a 'GH' effect so I am basically only looking for new insights, blogs 'explaining the fndamentals' are of little use to me. What probaly upsets you is that I require the fundamentals to be re-examined. Typically the 'fundamentals' explain that 'The Earth emits like a black body' possibly with 'in the infrared'. A statement like this is nonsense because nothing that reflects like the Earth, with its albedo, can ever emit like a black body; such a statement breaks just about everything known and long established about electromagnetic radiation. And when a VIP of the IPCC writes in his book on Atmospheric Physics that he 'assumes that Earth radiates like a black body', then I am certain there is something deeply wrong with his 'climate theory'. I do think that the climate change hypothesis needs very careful examination and it this 'black body' type of assumptions, making nonsense of both 1st & 2nd laws of thermodynamics, that concerns me the most.
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  10. Re #258 archiesteel you wrote:- "CO2 is largely transparent to visible light." I think the albedo is also to be found in both the IR and UV bands.
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  11. damorbel - You have not responded (or, apparently, read) my posts here (re: your post which actually confirms the greenhouse effect) or here (on albedo). Let alone the this restatement of the actual topic of the thread. You've agreed with every component of greenhouse gas heating, yet continue to insist that the result of those physics does not occur. If you "require the fundamentals to be re-examined", and feel the textbooks are wrong, then write a paper proving that, and get the textbooks changed. Insisting on your mis-interpretation of physics and rejection of established science with no evidence is not going to convince anyone. You've been pointed to appropriate references time and again, and appear to just reject them where they conflict with your pre-conceived notions. At this point your postings are simply noise - if you have questions, then pay at least some attention to the answers. I don't know if you are genuinely confused as to the physics or trolling - at this point there is no difference from my point of view. I consider this discussion at an end.
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  12. Re #261 KR you wrote:- "You have not responded (or, apparently, read) my posts " And you linked to your #250 where you wrote:- "By George, I think you've got it! Even if you don't recognize it." Is there something about these posts that needs a reply? I have the impression you were making an effect rather than an argument. I have made a number of relevant arguments about the direction of heat transfer (hotter to colder) and the standard response comes 'back radiation' which is only half the matter it is the difference of radiation 'in' and 'out' that determines temperature change. Now surely that is something for such discussion such as this? You wrote "I consider this discussion at an end." I'm sorry but when you make remarks such as "your postings are simply noise" then I begin to understand what your real problem is, and its nothing to do with the 2nd law of thermodynamics.
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    Moderator Response: Please avoid arguments about who did or did not respond, as they are off-topic to the scientific content of this post. Your comments regarding direction of heat transfer have been addressed multiple times in this thread. If you have specific rebuttals to these comments then please address the points directly.
  13. damorbel - Did you read the rest of my post here? Demonstrating (using your formulation of energy flow) that outgoing energy from the ground is decreased by the presence of greenhouse gases? And that (as you agreed here) temperature will change until outgoing energy again equals incoming energy, in this case increasing to match decreased outgoing energy at any particular temperature? GHG's -> decreased outgoing energy -> temperature rise -> outgoing equals incoming - > Greenhouse effect, Q.E.D. You've agreed to all the components of greenhouse heating, yet still disagree with the conclusions. You insist that textbook fundamentals are incorrect without proof. I cannot consider those reasonable positions to take, and hence not worth my while discussing. As to my tone, I must admit to a bit of sarcasm after 262 comments on the topic of bad piece of science writing published in an off-topic journal.
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  14. RE #259: damorbel at 03:54 AM on 17 December, 2010 Can you please clarify exactly what your point is? Are you complaining that people refer to the earth as a black body? - Isn't a black body a theoretical thing? - Does it help if you just read that as "grey body"? - How does your concern over the black body terminology impact the earth's emission of IR radiation? Are you suggesting that the earth doesn't emit IR? Honestly, I can't find what your point is. Just come out and state it.
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  15. Since any actual measurement agrees with textbook theory, I think that burden in on damorel to produce evidence of a measurement that disagrees. Of course this would also involve understanding what the textbook physics actually do predict rather than some imagined belief about the physics.
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  16. @damorbel: "I think the albedo is also to be found in both the IR and UV bands." Not really. Albedo concerns visible light. I think at this point it's pretty clear you don't know what you're talking about, and that your credibility is shot. Time to use another username!
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  17. That was an interesting exchange between damorbel and the home team, which, as evidenced by the language of archiesteel, claims a victory, complete with disparaging remarks. However as far as I am concerned the verdict was "not proven". And that seems to be the case amongst experts at the highest level, judging by the exchanges I have read about so far. Surely if both sides are as sure as they claim to be in their interpretation of the physics of the atmosphere, isn't it possible to set up a handful of experiments( the details of which have been agreed by both parties) and run them( irrespective of the fact that they have been done before and the results of which are thought to be highly predictable)? And see what happens. A few simple controlled experiments would end all this obfuscation. One of the conditions is that the results be released over the internet, immediately they become known.ie no interpretation for the general public and absolutely NO peer-review.Isn't THAT "Science in action"? Only then will the layman have something solid on which to base an opinion.
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  18. AWoL do you think that whoever comes with such a misunderstanding/misinterpretation of a century old science, scients should start from scratch to demonstrate something so well known? Are you asking scientists (or anyone else) to go back to the 18th century? The reference community of scientists is that of other scientists and none of them would make such weird claims.
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  19. AWoL, you misinterpret what you read. As KR pointed above, Damorbel agreed to ALL the components of the GH effect. Yet he argues against what comes out of that effect. Fortunately, we don't need arguing about that (or much of anything else for that matter) since the result of that effect is well accounted for by both line by line radiative transfer models and observations. There is an abundant litterature treating of IR radiation at the surface, in the bands of GH gases. Ultimately, this is the real proof of the existence of the GH effect. If there was not a GH effect theory, we would have to come up with an explanation for that downwelling IR radiation and it would have to account for the fact that it is in the bands of the GH gases. Asd for your concept of how scientific results should be released, your own inability to sort out among what you read here indicates how bad an idea that would be.
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  20. Ok, AWoL. You come up with an initial design for a set of experiments, and then open up the design to the community and we'll adjust as necessary. Then we'll do them. So let's see some design statements. Might a pyrgeometer be involved? Maybe John should have a new thread on this: "Backyard Science: Providing Evidence for the Layman when Established Science Just Isn't Good Enough (or is thoroughly corrupt or too obtuse or whatever)"
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  21. #271: "Backyard Science: " Maybe AwoL missed the infamous Dr. Spencer experiment and subsequent articles, which were mentioned back at comment #70 and probably don't need further rehash. An interesting thread, though, might be 'What goalpost moves are required when a denier has to argue with another denier's results?'
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  22. AwoL - before you think of new experiment, perhaps you might like to examine the many experiments already done. However, I am fully in agreement that nature is the arbiter. I have already suggested damorel provide an experiment which he/she thinks vindicates imaginary physics over textbook version. Certainly feel free to pose or demonstrate one also - though in this area I suspect the experiment is likely to have been already covered by painstakingly intricate work in the 1950s.
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  23. 3 posts removed now , so obviously hit the spot. I would like to reply, scaddenp, but althought I feel free, I am not free.....if you see what I mean.
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    Moderator Response: [muoncounter] No, no one sees what you mean. If you keep your posting to scientific questions and stop throwing around innuendo, suggestions of conspiracy, whining about moderation and such tripe, in keeping with the comment policy, you wouldn't have such problems.
  24. "althought I feel free, I am not free.....if you see what I mean." I don't. It is clear that you are not free to accuse people of colluding to deceive, engaging in conspiracy, commiting fraud and a number of other things that are outlined in the comment policy. If you want to accuse scientists of fraud, you can go rant on CA or WUWT. I had a great many of my comments taken down on this site, I could always get a clue why they were. Get a grip. If you have something of substance to say on the mattter, say it. If it is not of substance, off topic, or belongs in the categories listed above, keep it to yourself
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  25. This is simply wrong. You are trying to compare a heat generating source - a human body - with a heat recipient. Our body loses heat by conduction of heat to the atmosphere and then by convection of warmed air. Clothes and blankets simply keep the warm air close to our body. We radiate heat at the same rate whether we are naked or clothed. We cannot heat up our immediate environment more than our core body temperature. Radiation is such a poor method of heat transfer that we can keep warm. Remember wind chill if you don't think convection is the major factor in heat transfer in an atmosphere. Your explanation also completely fails to deal with the requirements of thermodynamics which state that heat cannot flow from a hot object to a colder object unless there is work performed. Your answer totally fails to explain the work performed and therefore completely fails to refute the claim you set out to refute.
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    Moderator Response: (DB) The law says NET heat cannot flow from cold to hot, so your comment is self-refuted.
  26. Rosco - this is basic version. This argument has been done to death at in here. I note some confusion on Trenberth. I suggest you might like to get your head around some basics at Science of Doom (and the many other articles there). In short, the physics is more subtle than you think it is.
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  27. Re #275 "Moderator Response: (DB) The law says NET heat cannot flow from cold to hot, so your comment is self-refuted." There is no other kind of heat tranfer than 'NET' heat transfer. It should be obvious that there is only 'direction of transfer'. Heat transfer from the surface to the atmosphere is 'positive' in the direction away from the surface, the surface is thus cooled by the 'NET' transfer of heat from the surface to the troposphere. Were there to be any surface warming effect it would require a 'NET' (!) tranfer of heat to the surface, which in unusual circumstances actually can happen in the troposphere (with temperature inversion). At the very low pressure in the stratosphere there is a permanent temperature inversion from lat.-55 to lat.+55 caused by O2 absorbing energy from the UV part of the solar spectrum and making O3, this solar energy causes a temperature inversion that defines the stratosphere. This inversion suppresses convection locally, which is the reason turbulance is very much reduced in the stratosphere. The heat absored from UV is small (5%?) compared with the rest of the Sun's energy, and the absorption, by O2 (and O3) takes place at stratospheric altitudes, it is also complete; so it (the UV heat) has little or no effect on the surface.
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    Moderator Response: [Dikran Marsupial] You are incorrect and would benefit from considering the advice you are given in more detail. Consider a binary star, one a blue giant, the other a normal main sequence star, much like our own Sun. Clearly the blue giant is the hotter and will have a warming effect on the other star because the NET transfer of heat will be from the blue giant to the main sequence star. However this does not mean that there is no transfer of heat in the other direction. The main sequence star emits photons in all directions, including in the direction of the blue giant. Each of those photons transfers heat energy from the cooler star to the hotter star. Howeve this does not violate any law of thermodynamics as the blue giant transfers more energy back to the main sequence star. This there is another kind of transfer other than "NET" and there is not only one direction of transfer, it is bidirectional, and the laws of thermodynamics only constrain the net statistical behaviour of the transfer of heat. This has been explained repeatedly on these threads already.

    Secondly, surface warming does not require a net transfer of heat from the atmosphere to the surface. If I put on an extra blanket at night I warm up, but there has not been a net transfer of heat from the blanket to my body (we know this as the blanket warms as well). This is another canard that has been refuted repeatedly on these threads.

    I suggest DNFTT, if damorbel still cant understand this after having it explained so many times, one more try is unlikely to work (yes I know there is some irony there, given I have just pointed it out again ;o)
  28. Re #277 "Moderator Response: [Dikran Marsupial] You are incorrect and would benefit from considering the advice you are given in more detail. Consider a binary star, one a blue giant, the other a normal main sequence star, much like our own Sun. Clearly the blue giant is the hotter and will have a warming effect on the other star because the NET transfer of heat will be from the blue giant to the main sequence star." I would agree with you if the Earth was a significant source of energy like either the red or the blue stars you refer to. But they are not relevant to the Earth which, at the most, sources 0.1W/m^2 in comparison with the Sun (6.3x10^7 W/m^2). The temperature of the stars you refer to are surely determined by the energy they source from (local) internal nuclear reactions (do you agree about this?) whereas the temperature of Earth is decided by the temperature and distance of the Sun. Further you write "If I put on an extra blanket at night I warm up, but there has not been a net transfer of heat from the blanket to my body " Like the red and blue stars your body is a heat source (about 150W in total for a live but resting body). Blankets slow the rate this internal heat escapes to the surroundings, meaning your body is, due its internal heat, at a temperature above that of the surroundings. If you die, your 150W comes to an end and your body temperature will fall to that of the surroundings, slowly if it is well insulated by blankets, quickly if uninsulated. Thereafter your body temperature, insulated or not, will follow the environmental temperature. I have mentioned this before, do you think it is incorrect? I'd be very interested to hear another explanation. Sorry, I do not understand cryptic expressions like 'DNFTT'.
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    Moderator Response:

    [Dikran Marsupial] The Earth is a significant source of heat with respect to the atmosphere, which was the point. Solar radiation (mostly visible) heats the surface, which then emits IR that heats the atmosphere. However the atmosphere does emit IR downwards to the surface and hence there is a transfer of heat from the atmosphere to the surface, but it is smaller than the transfer from the surface to the atmosphere (hence it the laws of thermodynamics are not violated).

    The example of a binary star was to demosntrate that there is a bidirectional transfer of heat between any two objects above zero degrees Kelvin, but the net flow is from warmer to cooler. Over-extending an analogy beyond what it was intended to show is a common rhetorical tactic to avoid taking on board the substantive point. Please go back and think about the analogy in the light of what I have just written.

    Yes, the heat source for the blanket example is the body, which is very apposite to a discussion of the greenhouse effect. The sun does not substantially warm the atmosphere (which is largely transparent to visible light). It warms the surface, which then emits IR which does warm the atmosphere. From the point of view of the atmosphere, it is not being warmed from above by the sun, but from below by the Earth. The fact that the Sun is the source of the Earths heat is irrelevant; the sun is ultimately the source of the heat from my body under the blanket as well.

    The paragpraph about what happens if I die is irrelevant (and another example of over-extending an analogy).

    DNFTT means "do not feed the troll". Repeatedly bringing up the same points again and again that have been answered already many times, is indistinguishable from trolling. If you want to dispell the appearance of trolling, you need to engage with the explanations you are given, rather than just seeking to over-extend analogies etc.

    [DB] As for "DNFTT" that is an acronym for "Do Not Feed The Trolls". It is a suggestion given to the regular participants in an online forum when a newcomer has clearly established 2 things: 1. That they have no interest in actually learning about the topic and 2. Their continued participation in the forum is an exercise designed to waste the time of others by engaging them in conversations that lead nowhere. Similar to Napolean's efforts in Russia or the Soviet's efforts in Afghanistan.

  29. Re #278 When you write "The paragpraph about what happens if I die is irrelevant (and another example of over-extending an analogy)." you illustrates the matter in hand exactly. This is further exemplified by the perhaps more relevant comparison I made with the Sun when I wrote:- "But they are not relevant to the Earth which, at the most, sources 0.1W/m^2 in comparison with the Sun (6.3x10^7 W/m^2)." Do you not agree that the 0.1W/m^2 produced by the Earth, mainly by U238 and K40 has almost no affect on its surface temperature? With this 0.1W/m^2 the Earth would have a temperature of about 50K, whereas your stars are producing somwhere about 6.3x10^7 W/m^2. Think of it this way: it doesn't matter where a particular star is found, it produces it own heat which determines its temperature; whereas a planet's temperature is strictly related to is distance from the star; an extreme example is a comet which has a very variable temperature, only warming up for a short period while close to the Sun. The Earth would have a similar temperature cycle if it shared a comet's orbit whether it had a CO2 atmosphere or not. The relevance of this is the star's temperature is independent of its position in the same way the temperature of your body, wrapped in insulation, is substantially independent of its position; but strongly dependent on the amount of (internal) heat (150W) it generates and the amount of insulation surrounding it. I am bothered that you do not appear to see the comparison between the temperature of a body (or a star) generating internal heat and a planet (or a dead body) that does not generate any internal heat. This is not playing games like trolling, as you seem to think, but it is serious science, the point I am making between heat generated internally (or not, as the case may be) is quite serious and is at the heart of a discussion, while you only see as me attempting to disrupt the discussion. I am very sorry if you feel I am just [trying] :- "to waste the time of others by engaging them in conversations that lead nowhere". This is certainly not the case and I am sorry if anything I have written gives that impression but I stand by the facts I have recounted, heat originating inside a body, any body, has a quite different effect than heat arriving from outside it.
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    Moderator Response: [Dikran Marsupial] I'm sorry, but this discussion is going nowhere. Nobody disputes that the ultimate source of the heat in the atmosphere is the Sun and that the heat generated from within the Earth by e.g. radioactive decay is insignificant. Nobody is disputing either of these facts, and neither has any relevance whatsoever to a discussion of the application of the second law of thermodynamics to the greenhouse effect. Hence you are deflecting the discussion of the substantivie issue with digressions of issues that are not contested and which have no relevance. That is indistinguishable from trolling.

    You are incorrect if you think that a planets temperature is strictly related to its distance from its star and that the presence of CO2 makes no difference. This is directly refuted by the observation that the surface of Venus is warmer than the surface of Mercury.

  30. Damorbel, do you really think that you can fool anyone here with your nonsense? You have demonstrated in the past, repeatedly, on this very thread, that you are a troll. You have many times touted around physical laws of which you had not the foggiest understanding. You have argued one way, then another, contradicting yourself for the sake of argument. You have lectured others on physics, yet demonstrated a fluency with the science that is best qualified as pitiful. Despite all the asnwers addressed to your confused posts, you don't seem to have learned anything. You are not a skeptic, you are not a dissenting voice, you are just a waste of time. You have benefited of seemingly infinite patience in spite of repeated attempts to start non discussions leading nowhere. You wait for a number of weeks and then do it again. It is not even irritating anymore, it is just pathetic. I have been subjected to snark on SkS, I have endured streams of insults and xenophobic prejudice, I have seen people arguing in bad faith using dishonest rethoric, others laying blanket accusations of fraud with nothing to back them up, but I have never proposed on any forum that someone be permanently banned. I also do not personally know of anyone who was ever banned from SkS. However, I am now convinced that it would be advisable in your case, for objective reasons that will be obvious to the reader courageous enough to peruse your "contribution" (the words feels misused) on this thread. There should be a limit to how much BS can be tolerated for the sake of "balance." You have already passed that limit, in my opinion. I am not in a position to recommend that you be banned but I find it evident that everyone would benefit from it, probably even yourself.
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  31. Re #280 Philippe Chantreau, you wrote:- "You have many times touted around physical laws of which you had not the foggiest understanding." I do think it would be better if you explained just what it is you find incorrect in my postings. A new reader would not easily grasp from your #280 just what my arguements were, let alone what was wrong with them. In short, what information should we gain from #280?
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    Moderator Response: [Dikran Marsupial] #280 said very little about what your argument actually is, and I suspect was not intended to. It was a comment on the rhetorical nature of your argument. If you want a concrete example, I pointed out that the fact that the mean surface temperature of Venus is higher than that of Mercury directly refutes an argument you made. However rather than refute the counter example, or admit that your argument was wrong, you ignored it and went back to over-extending an analogy in a way that is not relevant to the dicussion (in a post deleted by another moderator). It should be no surprise that if you ignore counters to the arguments that you have made your actions will be viewed as trolling.

    The information you should take from #280 is that you should change your approach to the discussion and try and take on board the points made by the other contributors, and be less sure that you are right, and virtually every climatologist on the planet is wrong (those are not good odds).
  32. Nope, Phillipe--it just needs to be well-understood by anyone who reads this thread that Damorbel's assertions about the net result of an energy exchange (that energy only flows one way, from a hotter source to a colder source) have been thoroughly debunked about seven bazillion times in the main 2nd Law thread. By the way, Damorbel, how do you explain the simple experiment summarized in video here (50 second mark)? Note that the right jar has the benefit of convective access to the room air.
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  33. Re #281 Moderator Response: [Dikran Marsupial] You write " If you want a concrete example, I pointed out that the fact that the mean surface temperature of Venus is higher than that of Mercury directly refutes an argument you made.... " Dikran, the distinctions between Venus and :Mercury are rather large - Mercury has no atmosphere and the dark side has a temperature of 100K (because it rotates in about 58.7 Earth days) By contrast Venus has an atmosphere about 90 times as dense as that on Earth, it rotates in about 224.7 Earth days. However its dark side temperature is the same as its sunlit side (as are the poles). This is because Venus behaves like a gassy planet rather than a rocky one. A gassy planet has a strong increase in temperature with depth in the atmosphere, it is the same with Jupiter. You refer to one of my posts as "a post deleted by another moderator" I was wondering about this. How do you expect me to make a discussion when this sort of thing happens? I would like to refer to that post, you have whycannot other people see it? So far Dikran, you have made no comment on the distinction I draw between a body with a an internal heat source (a star) and a body without an internal heat source a planet or a comet. Bodies with an internal heat source is heated in an entirely different way from one without an internal heat source. Re #281 DSL, I have looked at your video. As far as it goes (showing gases absorbing heat and rising temperature in consequence) but it falls down hoplessly in that, with a rising temperature, it is clearly out of equilibrium. Furthermore it doesn't show that Greenhouse Gases emit radiation equally as well as they absorb it when in equilibrium (steady temperature). For this reason the video does not represent the Earth and its atmosphere - Sorry! This was discovered by John Tyndall - it was mentioned in his 1862 paper. PS You also mentioned "Note that the right jar has the benefit of convective access to the room air." Does this make any difference? Why were glass jars necessary for the demonstration? The Earth has no glass jars. Surely glass jars have some effect in the demonstration, otherwise they wouldn't have been be used, would they.
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    Moderator Response: [Dikran Marsupial] I see that yet again you are unable to question your own position. Yes, mercury has no atmosphere, but it was you that was arguing that CO2 in the atmosphere has no effect on temperatures not me.

    Your post was deleted (not by me) because it was yet another example of one of your posts that made the same points yet again without taking on board any of the counter arguments that had been presented.

    I have commented on the distinction that you draw between a body with an internal heat source and one without, I pointed out that the distinction was (i) irrelevant to the discussion of whether heat flow is bidirectional or not (which depends only on their temperature) and (ii) it is irrelevant to the greenhouse effect because as far as the atmosphere is concerned it is heated from below by IR radiated from the surface, not from the Sun above. The fact that the IR radiated from the surface was caused by absorbtion of visible light from the Sun does not change that. This is why your posts are trolling; your arguments have been repeatedly addressed and you ignore the counters, as you have just done here yet again.
  34. damorbel@283 "Why were glass jars necessary for the demonstration?" Seriously? How else would they let in light/radiation and hold in CO2?
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  35. damorbel#283: "Venus behaves like a gassy planet rather than a rocky one." Venus' average density is 5.2 gm/cc; a rocky start for your point. But this thread is not about Venus. "the distinction I draw between a body with a an internal heat source (a star) and a body without an internal heat source" I'll bite. Stars and planets are not the same. A planet receives energy from its nearby star; heat is retained by the planet when it has a greenhouse atmosphere. What was your point? BTW, you might have a look at Doug Cotton's 'earth-climate' web site and set him straight over the question of internal heating.
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  36. Agreed with #285. Doug Cotton's site is the venue of choice for you Damorbel.
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    Response:

    [DB] Added link.

  37. Philippe and DB, that would be about as exciting as watching an iron ball rust, but the physical model that such a conversation would generate would be an all-time classic. Ok, ok -- I'm tempted, but DNFTT it shall be.
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  38. Re #283 Moderator Response: [Dikran Marsupial] you wrote:- "you that was arguing that CO2 in the atmosphere has no effect on temperatures not me" With thermodynamics you have to be precise, What temperature are you referring to when you speak of a planet's temperature? [trolling snipped]
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    Moderator Response: [Dikran Marsupial] Sorry this is blatant trolling. I specified mean surface temperatures (I have put it in bold now to make it more obvious), so I specified exactly what I meant. Enough is enough, if you continue in this manner I will reluctantly recommend that your posting privelidges are rescinded. It is not acceptable for any poster to disrupt the discussion in this manner.
  39. Re #288 [trolling snipped] Moderator Response: [Dikran Marsupial] you wrote:- "It is not acceptable for any poster to disrupt the discission in this manner" Dikran, I just do not agree with your physics.
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    Moderator Response: [Dikran Marsupial] Note yet again I have pointed out your error (I did specify what kind of temperature measurement I discussed) and again you do not acknowledge your error (if it was me I would have appologised - we all make mistakes, it is no big deal, unless you can't acknowledge them, in which case you have entirely the wrong attitude for scientific discussion).

    If you don't agree with my physics, just possibly it is because your understanding of the phycics is wrong, rather than that of the worlds climatologists and physicists. However you will convince nobody that your position is correct if you conduct the discussion in the manner that you have chosen.

    To be clear, we welcome a discussion of the physics, but not constant repetition of arguments that have been refuted repeatedly already on this thread and on others, without addressing those refutations
  40. Re your Moderator Response: [Dikran Marsupial] to #283 "I pointed out that the distinction was (i) irrelevant to the discussion of whether heat flow is bidirectional or not (which depends only on their temperature) " You appear to want me to accept that heat flow can be "bidirectional" in some way. As far as physics is concerned I think this is where we disagree. Heating (or cooling) results in an increase (decrease) in temperature difference between two locations, a given location can only have one temperature so it is quite impossible for one location to have, simultaneously, a rising and a falling temperature. If the energy entering this location is balanced by the energy leaving it, as for example in the atmosphere, the temperature of the atmosphere will not change due to changes in GHG concentration, since GHGs both absorb and emits radiation at a given temperature, nothing will be changed if the amount of CO2 is increased (or decreased). Put another way, if there was no CO2 at all the radiation from the surface would replace that from the atmospheric gases, there would no radiative temperature change. Of course the surface is warmer than the upper atmosphere but that is due to gravitation, not radiation. Further you wrote:- (ii) it is irrelevant to the greenhouse effect because as far as the atmosphere is concerned it is heated from below by IR radiated from the surface, not from the Sun above" Have we not already agreed that the Earth doesn't have a significant heat source inside it? I agree that, if the Earth had a heat source inside it, big enough for, let us say 240W/m^2, then its would be closely related to the concentration of GHGs (and the emissivity of the surface). Further, as things stand, the Earth's average temperature would be what it is now, except it would be uniform (no frozen poles!) In my physics this planet, with its internal 240W/m^2, has a temperature that is very dependent on it emissivity. To explain, if it was a metal planet its surface temperature would be very high, highest of all if it was gold plated (gold has the lowest emissivity of all common metals). However if this (gold plated?) planet would have a GHG atmosphere its temperature would be lowered, the amount it was lowered would depend very much on the mass of the GHGs. But do not be surprised that such a planet (with no star nearby) would have a uniform surface temperature.
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    Moderator Response: [Dikran Marsupial] Your misunderstanding is right at the most basic level, so it would be a good idea to reach an understanding of heat flow before trying to apply it to the Earth.

    Do you agree that any body at a temperature above zero degrees Kelvin will radiate photons of energy? Please confine yourself to a direct answer to the question, rather than digress (which will prevent the discussion from making any progress).

    Damorbel please demonstrate that you are not just trolling and are willing to address the science by giving a direct answer to the above question, without digression. Your disruptive behaviour on these threads has led to the point where you need to demonstrate that you are able to learn and are not here simply to disrupt the discussion.

    Please can everyone else refrain from responding to damorbel until I have gone through the basics with him step by step.
  41. Re # 290 Moderator Response: [Dikran Marsupial] You wrote:- "Do you agree that any body at a temperature above zero degrees Kelvin will radiate photons of energy?" Um, it should be 'Kelvins', not 'degrees Kelvin'. The answer should be very clear from my posts. Yes bodies above 0K emit photons, with energy kT Joules, where k is the Boltzmann constant (Joules per Kelvin) and T is the temperature in Kelvins.
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    Moderator Response: [Dikran Marsupial] Thank you for a direct answer (however please don't get sidetracked by the details at this stage). Now lets consider an exactly spherical black-body at a temperature above zero Kelvin. Do you agree that it radiates photons at random time intervals in random directions, with a total power given by the Stefan-Boltzman law (power per unit surface area proportional to fourth power of temperature)? Do you agree with that (again please answer directly without digression).

    N.B. I will be teaching for the next four hours or so, but please be patient and wait for a reply before going any further.
  42. Ha! I made a mistake. What I wrote in #291 is the energy per particle, not per photon. The photon energy is hv where h in the planck constant in Joules per Hz and v is the frequency of the emitted radiation.
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  43. Re #291 Moderator Response: [Dikran Marsupial] You wrote:- "with a total power" - No, I don't agree. (1st Law of Thermodynamics)
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    Moderator Response: [Dikran Marsupial] Wikipedia defines the Stefan-Boltzman law as stating "that the total energy radiated per unit surface area of a black body per unit time (also known as the black-body irradiance or emissive power.), j*, is directly proportional to the fourth power of the black body's thermodynamic temperature T". In his book, "principles of planetary climate", Ray Pierrehumbert says that "the total power F exiting from each unit area of the surface of ablack body" is the Stefan-Boltzman law (page 142). Both of these support the statement I made. Are you saying that both Wikipedia and Prof. Pierrehumbert and his book are wrong on this point?

    The first law of thermodynamics says that energy can be changed from one form into another but not created or destroyed. This has no bearing on radiation from a black body as no energy is created or destroyed, merely radiated from the black body out into the surrounding space. The Stefan-Boltzmann law describes the rate at which energy is radiated.

    Now it is possible that you simply misunderstood, in which case, simply agree with the original statement and we can proceed. Otherwise please explain how the Stefan-Boltzman law violates the first law of thermodynamics. Please do so without digressing onto any other topic.
  44. Re #293 Moderator Response: [Dikran Marsupial] I quote your question:- " black-body at a temperature above zero Kelvin. Do you agree that it radiates photons at random time intervals in random directions, with a total power given by the Stefan-Boltzman law (power per unit surface area proportional to fourth power of temperature)?" My response was about 'total power'. Power is 'rate of change of energy' (dW/dt); but there is no need for a body at any temperature to lose energy if it is in a steady state, the mere presence of radiation does not mean a body is losing energy i.e. 'transferring power'. For example, a total internal reflecting cavity, whatever its temperature, does not lose any energy from its interior by radiation. Perhaps what you meant was 'a black body embedded in a black cavity at zero K'. The problem with the usual explanation of the Stefan-Boltzmann equation is that the photons emitted seem to disappear into some black hole which is not really a useful concept. In the real world 'black body' is also receiving photons from its environment.
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    Moderator Response: [Dikran Marsupial] O.K. in response to your obfuscation I will clarify the thought experiment. Consider a exactly spherical blackbody, in an vacuum of infinite dimension (so it is not recieving photons from its environment), without an internal heat source (i.e. it is not at a steady state, although that is irrelevant). Do you agree that it emits photons at random intervals and in random directions, such that the total power (over all of its surface area and over all wavelengths) is proportional to the fourth power of its temperature, according to the Stefan Boltzmann law?

    Please do not attempt to extend the thought experiment in any direction, and give a direct answer to the question. We will get onto the discussion of the temperature of the body and its energy balance later, once we have agreed the nature of its radiation.

  45. Re #294 Moderator Response: [Dikran Marsupial] you wrote:- "in an vacuum of infinite dimension (so it is not recieving photons from its environment)" Fair enough. And:- "Do you agree that it emits photons at random intervals and in random directions, such that the total power (over all of its surface area and over all wavelengths) is proportional to the fourth power of its temperature, according to the Stefan Boltzmann law? " Yes.
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    Moderator Response: [Dikran Marsupial] Good. O.K., so now lets introduce a second, identical blackbody (labelled "B") that is close to, but not touching the first ("A"). Unlike the first black body, the second is at zero Kelvin, so it is not emitting any photons. Do you agree that some photons from A will hit and be absorbed by B, thus transferring some energy from A to B?
  46. Re #295 Moderator Response: [Dikran Marsupial] you wrote:- "Do you agree that some photons from A will hit and be absorbed by B, thus transferring some energy from A to B? " Yes.
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    Moderator Response: [Dikran Marsupial] O.K., so now consider the case where B is above zero Kelvin, but cooler than A. (i) does this affect the radiation of photons from A, or does it continue to emit photons with total power according to the Stefan-Boltzmann law (ii) Some photons from A will still hit and be absorbed by B, thus transferring some energy from A to B. Can we agree on that?
  47. Re #296 Moderator Response: [Dikran Marsupial] you wrote:- 1/"so now consider the case where B is above zero Kelvin, but cooler than A. (i) does this affect the radiation of photons from A," No. 2/"or does it [A] continue to emit photons with total power according to the Stefan-Boltzmann law " I think this is the same question, no 'or' about it; if A is still above 0K then A continues to emit photons, some of which will continue to be intercepted by B. 3/ "ii) Some photons from A will still hit and be absorbed by B, thus transferring some energy from A to B." Yes.
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    Moderator Response: [Dikran Marsupial] O.K., say B is at the same temperature as A. (i) Would you agree that the emission of photons from A is not affected by this and that it still emits photons at random intervals in random directions, such that the total power radiated is proportional to the fouth power of its temperature (as per Stefan-Boltzmann)? (ii) Would you agree that some of these photons emitted from A strike and are absorbed by B, transferring some energy from A to B?
  48. Re #296 Moderator Response: [Dikran Marsupial] you wrote:- 1/ "say B is at the same temperature as A. (i) Would you agree that the emission of photons from A is not affected by this ". Yes, as long as the temperature of A is not changed by this. 2/ "or does it [A] continue to emit photons with total power according to the Stefan-Boltzmann law " I think this is the same question, no 'or' about it; if A is still above 0K then A continues to emit photons, some of which will continue to be intercepted by B. 3/ "ii) Some photons from A will still hit and be absorbed by B, thus transferring some energy from A to B." No, there would be no change in the energy of either A or B because they are at the same temperature.
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    Moderator Response: [Dikran Marsupial] This is obfuscation. I explicitly said that the temperature of the bodies was a point that will be discussed later. I asked whether you agree that the emission of photons from body A remained as before, with photons emitted at random intervals and in random directions with total power given by the Stefan Boltzman law (which already describes the dependence on temperature).

    To avoid any further obfuscation, I will re-word the question. Do you agree that body A will radiate photons in random directions at random intervals, with total power proportional to the fourth power of the temperature of body A (i.e. according to the Stefan-Boltzmann law), and that this remains true regardless of the temperature of body B?
  49. Re #296 Moderator Response: [Dikran Marsupial] You wrote "This is obfuscation. I explicitly said that the temperature of the bodies was a point that will be discussed later" Temperature will be discussed later? Then what do you mean when you write:- 1/(in #290):- "Do you agree that any body at a temperature above zero degrees Kelvin will radiate" 2/(in #291):- "power per unit surface area proportional to fourth power of temperature" 3/(in #294):- "is proportional to the fourth power of its temperature, according to the Stefan Boltzmann law?" 4/(in #295):- "Unlike the first black body, the second is at zero Kelvin" 5/(in #296):- " so now consider the case where B is above zero Kelvin, but cooler than A" 6/(in #297):- "O.K., say B is at the same temperature as A." And so forth?
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    Moderator Response: [Dikran Marsupial] Your pedantry does you no favours. O.K. I shall reword it for you, we will discuss the change in temperature of the two bodies later. Now please give a direct answer to the question I posed.

    If you want to demonstrate that you are merely a troll, this sort of pedantry, whilst avoiding answering the question is exactly the right way to go about it. I am trying to do you a favour here by encouraging a more productive discussion by going through it step by step to see if you are willing to engage with the discussion. You a wasting an opportunity here, but it is your loss.
  50. Dikran, you are wasting your time.
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    Moderator Response: [Dikran Marsupial] Yes, I know I probably am, but I am trying to give damorbel a chance to demonstrate that he is more than just a troll and willing to engage in a proper discussion. Currently he is wasting the opportunity with extreme pedantry.

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